Movable grates for furnaces, particularly refuse incinerators

ABSTRACT

The invention relates to a movable grate for furnaces, particularly refuse incinerators. For providing movement and spreading of the refuse to be incinerated the grate is arranged to impart a wavelike movement to the refuse. According to the invention, the grate is composed of steps which are relatively movable in opposite directions and each of which is pivoted about a central axis extending through the respective step, said step being equipped with a drive including reciprocating means which impart a rotary motion to the grate steps about the axes so that adjacent grate steps will move in opposite directions. Within a group of grate steps thus caused to move alternately in opposite directions, a synchronizing mechanism is arranged between the axes of a pair of adjacent steps.

United States Patent [72] Inventors NilsGustav Axel Nobelius Sven Arvid Alexandersson Farsta, Sweden [73] Assignee [32] Priority Apr. 4, 1968 [33] Sweden 1 1 4489/68 [54] MOVABLE GRATES FOR FURNACES,

PARTICULARLY REFUSE INC INERATORS 1,577,407 3/1926 MacKay 2,385,027 9/1945 Preston 110/39 3,266,447 8/1966 Turner et al... 110/39X 3,418,998 12/1968 Holstein et al 126/176 Primary ExaminerEdward G. Favors Attorneys-Ralph E. Bucknam, Jesse D. Reingold, Robert R.

Strack and Henry A. Marzullo, Jr.

ABSTRACT: The invention relates to a movable grate for furnaces, particularly refuse incinerators. For providing movement and spreading of the refuse to be incinerated the grate is arranged to impart a wavelike movement to the refuse. According to the invention, the grate is composed of steps which are relatively movable in opposite directions and each of which is pivoted about a central axis extending through the respective step, said step being equipped with a drive including reciprocating means which impart a rotary motion to the grate steps about the axes so that adjacent grate steps will move in opposite directions. Within a group of grate steps thus caused to move alternately in opposite directions, a synchronizing mechanism is arranged between the axes of a pair of adjacent steps.

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PATENTVED JUN nan SHEET t UP 6 PATENIEIJ JUN 1 mn Sam 5 or 6 PAIENTEDJUNHQTI 358L684 sum 5 6 MOVABLE GllkA'lllES ll 'flllt lflUhtNAClEfi, PARTICULARLY litlElFlUSlE INCINIERATUIW This invention relates to a movable grate for furnaces, incinerators etc. in which a plurality of grate portions or steps which are relatively movable in opposite directions, together constitute an inclined grate surface comprising one or more sections, and in which a drive is so connected with the steps of the grate that during the movement of the grate a wavelike movement is imparted to the refuse to be incinerated on the grate so that said refuse is fed downwardly.

The invention has for its object to provide a new type of grate and a drive and synchronizing mechanism therefor which with the aid of a source of drive power for each section of the grate in which the steps pivot at the same rate, permits an optimum utilization of the grate. The main characteristic features of the invention reside in that the grate comprises a number of steps disposed transversely of the inclination of the grate surface and suitably brought together in groups or sections, said steps of the grate in turn consist preferably of a number of juxtaposed grate rods supported by a shaft assembly and each grate step is arranged to pivot or rotate about a radially nondisplaceable shaft which is centrally localized in respect of the grate step or the rods thereof, that the shaft assemblies supporting the grate steps within a portion of the grate where the steps are adapted to move at the same rate, are actuated by a device producing rocking of the grate steps, juxtaposed shaft assemblies being actuated by transmission means acting in opposite directions, and that means synchronizing the. pivoting or rocking movements of the shaft assemblies is disposed between two juxtaposed shaft assemblies, said synchronizing means being adapted during the movements of the" grate steps to maintain a predetermined clearance between the edge portions of the grate steps.

A preferred embodiment of the invention will be described more in detail in the following, referencebeing had to the accompanying drawings in which:

FIG. I is a diagrammatic cross-sectional view of a grate;

FIG. 2 is a view of a supporting beam on one side of the grate with the shafts of the grate steps mounted therein, and the drive of the lower section;

FIG. 3 is a view on a larger scale ofa shaft end with the lever arm thereof seen in the direction of the shaft;

FIG. 41 is a view of the same detail as in FIG. 3 as seen at right angles to the direction of the shaft;

FIG. 5 is a view on a smaller scale of the synchronizing mechanism which is disposed between two shafts of the grate steps;

FIG. 6 is a cross section of a divided grate step.

The grate comprises a number of steps ll arranged in the form of stairs. Each step is composed of a number of juxtaposed rods secured to a common shaft 2. All steps except the first and the last steps which connect onto curving end pieces 3 have the same cross section, and the shafts 2 extend along the central median line of the steps. The opposite edges of each step are of substantially symmetrical shape, but the downwardly facing edge 4', as viewed in the grate direction, is slightly curved downwardly while the upwardly facing edge d" is slightly curved upwardly. This arrangement provides a selfcleaning effect as the downwardly curving front edge portion of a superjacent grate step at its pivoting movement will push away possibly remaining unburnt refuse rests at the rear edge portion of the subjacent grate step.

The shafts 2 of the grate steps which shafts support the grate rods and which between journals at the ends present a cranklike staggered fastening element for the grate rods, are mounted-as will appear from FIG. 2.-in longitudinal beams or like members L; which extend on either side of the grate. Located between the edges of the grate surface and said beams are boundary plates 6. The outer sides of these plates are cooled by the passing air. Each step of the grate is provided with round end discs l (FIG. 5) which fit into openings in the boundary plates and prevent refuse particles from jamming between the end of the grate step and the boundary plates during the movements of the grate.

The grate illustrated is divided into two sections which have different rates of movement. Of the shafts 2 shown in FIG. 2, the five uppermost ones IV belong to one section while the six lowermost ones VII-XII belong to the other section. The shaft VI situated between the two sections is divided so that one-half of the shaft follows each section.

The division of the grate into two sections implies that two independent drive units must be associated with the grate. These drives are individually controllable. In the following description, only the drive of the lower section VII-XII will be described since the drive units of the two sections are mainly identical, apart from the relative localization of details.

In grates of the design here described, juxtaposed grate steps are to be pivoted in opposite directions for attaining the desired wavelike movement of the grate surface. At the same time the movement between the grate steps shall be so adapted that during the entire pivoting movement no undesired openings occur between the grate steps through which refuse particles can fall.

As every second grate step within each section shall pivot in the same direction and at the same rate it has proved suitable to provide all shafts 2 with a lever arm '7 and to interconnect, with the aid of links or like elements 3, the odd steps VII, IX and XI to one group and the even steps VIII, X and XII to another group. To the latter group is connected also the shaft portion of the steps VI, which is to follow the movements of the lower section.

As will appear from FIGS. 3 and 41, the shafts 2 are connected with the lever arms 7 by resilient means in order that objects penetrating between the grate steps during the pivot ing movements shall not damage the drive or the links or lever arms. The lever arm 7 is mounted for free swinging movement about the shaft 2 and carries a pack ofleaf springs 10 at an upwardly extending member 9. Two projections 11 ofa yokelike design are fixedly arranged at the shaft of the grate step. Placed at the outer ends of the projections 11 are setscrews 12 which engage the end portions of the pack of leaf springs 10 the central portion of which is connected to the lever arm 7 by means of screws or like elements 13. When the lever arm 7 is swung the shaft 2 will normally be brought along in the movement, but if the movement of the grate step and thus of the shaft is prevented the movements of the lever arm will wholly or partly be taken up by the pack of leaf springs 10 without any rotary movement of the shaft 2. The spring assembly is also intended to prevent that impacts from falling heavyweight articles are transmitted to the drive. The risk of such impacts is greatest at the uppermost steps of the grate, which as a rule are situated beneath the charging hopper of the incinerator or furnace.

To provide the desired synchronization between the two groups of grate steps which are swung in opposite directions, it is possible to choose between several procedures. One procedure is to provide, at two adjacent shafts, arms which are directed towards and slightly overlap each other. At the end of each arm there is mounted a roller or other friction-reducing element which is allowed to roll on the opposite arm. In addition, there is mounted between the two arm ends a spring means which tends to keep the overlapping arm portions applied against each other. When one arm-the grate step-is swung the other arm-the grate step-will be swung by the same amount, the spring means constantly keeping both arms and grate steps applied against each other. Another procedure is to provide the two adjacent shafts with gear segments which are caused to engage each other. The shape of the segments can be varied in dependence on variations in the cross-sectional shape of the steps. Still another procedure is to dispose the lever arms 7 associated with the shafts of the grate steps in such a manner that they extend in opposite directions and to connect the lever arms on each side to a link as well as to intereonnect the link ends with a pair of rods converging at a point. At said point the pair of links is connected to a means providing the pivoting movement and being in turn caused to follow a curving path so that the location of the junction point is displaced during the movement in either sense transversely of the direction of motion.

In the preferred embodiment illustrated in FIG. 5 the need for complicated curves and the like for the synchronization of the shafts has been eliminated in that there has been mounted at each of the two shafts to be synchronized an arm which extends at a 15 angle to a line interconnecting the shafts 2. The two arms 15 which are parallel in neutral position are each adapted to swing by 30 in each direction. The swinging movement thus covers a total of 60, which is as much as the grate steps 1 indicated by dotted lines are arranged to pivot. A link 16 adjustable in length is provided between the arms 15. The equally long anns 15 each are of a length slightly exceeding half the shaft spacing, which implies that in the neutral position shown the link 16 will be perpendicular to a line drawn between the shafts 2. By variation of the length of the link 16 the distance A between the facing curved edge portions of the grate steps 1 can be changed. In the position illustrated the length of the link 16 is so dimensioned that in the intermediary position there is formed a gap between the grate steps. Said gap serves to permit a flow of combustion air to pass therethrough during the phase of motion of the grate and thus to increase the amount of air supplied.

As will be seen from FIG. 2, one link 8 is connected with a hydraulic cylinder and piston assembly 19 which via the links 16, the synchronizing mechanism 15, 16 and the shaft lever arms 7 causes the grate steps to pivot. lt is readily realized that a speed-controllable electric motor or like means can be substituted for the hydraulic assembly.

Finally, FIG. 6 shows the divided grate step Vl supported by a shaft which is divided into two halves and one end of which is connected to the drive unit for the upper grate section while the other end thereof is associated with the drive unit for the lower grate section. In the Figure the step halves are in the position they occupy when the adjacent steps of both the upper and the lower sections are in their opposite positions.

We claim:

1. A movable grate for furnaces, incinerators and the like in which a plurality of grate portions or steps which are relatively movable in opposite directions, together constitute an inclined grate surface comprising one or more sections, and in which a drive is so connected with the steps of the grate that during the movement of the grate a wavelike movement is imparted to the refuse to be incinerated on the grate so that said refuse is fed downwardly, wherein the grate comprises a number of steps disposed transversely of the inclination of the grate surface and suitably brought together in groups or sections, said steps of the grate in turn consist preferably of a number ofjuxtaposed grate rods supported by a shaft assembly and each grate step is arranged to pivot or rotate about a radially nondisplaceable shaft which is centrally localized in respect of the grate step or the rods thereof, the shaft assemblies supporting the grate steps within a portion of the grate where the steps are adapted to move at the same rate, are actuated by a device producing rocking of the grate steps, juxtaposed shaft assemblies being actuated by transmission means acting in opposite directions, and means synchronizing the pivoting or rocking movements of the shaft assemblies is disposed between two juxtaposed shaft assemblies, said synchronizing means being adapted during the movements of the grate steps to maintain a predetermined clearance between the edge portions of the grate steps, said synchronizing means comprises an arm rigidly mounted at each of two adjacent shaft units which are adapted to pivot in opposite directions, said arms each being of a length slightly exceeding half the shaft spacing, being directed towards one another and being parallel in the parallel position of the grate steps supported by the shafts, and a link disposed between the free ends of the arms and preferably adjustable in length, said link being adapted in said parallel position to extend at right angles to the line of junction between the shafts.

2. A grate according to claim 1, wherein the grate steps are adapted to pivot through an angle of 60, each arm is adapted to rock through an angle of 30 in each direction from the position in which the two arms are parallel, and in their parallel position said arms make an angle of 15 with the line of junction between the shafts of the grate steps.

3. A grate according to claim 1, wherein the ad ustable link serves to control the clearance between the mutually overlapping edge portions of the grate steps in the neutral position thereof.

4. A grate according to claim 1, wherein the shafts of the grate steps have associated with them lever arms which are interconnected by rigid links so that the shafts of the grate steps which pivot in the same direction constitute a group united by means of links.

5. A grate according to claim 4, wherein the lever arms are adapted to actuate the shafts of the grate steps via spring means.

6. A grate according to claim 1, wherein the movements causing the shafts of the grate steps to rock are provided with the aid of a hydraulic cylinder and piston assembly or like speed-controllable drive unit.

7. A grate according to claim 1, wherein the rods collectively forming the grate steps at their ends have portions which project obliquely in opposite directions.

8. A movable grate for furnaces, incinerators and the like in which a plurality of grate portions or grate steps are relatively movable in opposite directions and together constitute an inclined grate surface comprising one or more sections, drive means connected with said grate steps and operable to move the latter in opposite directions whereby a wavelike movement is imparted to the refuse to be incinerated on the grate so that said refuse is fed downwardly, said grate steps being disposed generally transversely of the inclination of the grate surface and suitably brought together in groups or sections, each of said grate steps inturn comprising a grate shaft supported by a shaft assembly, each of said grate shafts being generally centrally disposed of its respective grate step, each of said grate shafts being nonradially displaceable, and each grate step is arranged to pivot about said radially nondisplaceable and centrally disposed shaft, said shaft assemblies supporting the grate steps within a portion of the grate where the steps are adapted to move at the same rate, said drive means producing rocking of the grate steps, said drive means including transmission means actuating said shaft assemblies to rock the latter in opposite directions, and means synchronizing the pivoting movement of the shaft assemblies, disposed between two juxtaposed shaft assemblies, said synchronizing means being adapted during the movements of the grate steps to maintain a predetermined clearance between the edge portions of the grate steps.

9. A grate according to claim 8, wherein the shaft of each grate step, to permit a central localization of the shaft relative to the step which has symmetrical cross section and is composed of a plurality of rods, comprises a journal arranged at each end and an intermediary portion which is radially offset in the manner ofa crank and to which said rods are secured. 

1. A movable grate for furnaces, incinerators and the like in which a plurality of grate portions or steps which are relatively movable in opposite directions, together constitute an inclined grate surface comprising one or more sections, and in which a drive is so connected with the steps of the grate that during the movement of the grate a wavelike movement is imparted to the refuse to be incinerated on the grate so that said refuse is fed downwardly, wherein the grate comprises a number of steps disposed transversely of the inclination of the grate surface and suitably brought together in groups or sections, said steps of the grate in turn consist preferably of a number of juxtaposed grate rods supported by a shaft assembly and each grate step is arranged to pivot or rotate about a radially nondisplaceable shaft which is centrally localized in respect of the grate step or the rods thereof, the shaft assemblies supporting the grate steps within a portion of the grate where the steps are adapted to move at the same rate, are actuated by a device producing rocking of the grate steps, juxtaposed shaft assemblies being actuated by transmission means acting in opposite directions, and means synchronizing the pivoting or rocking movements of the shaft assemblies is disposed between two juxtaposed shaft assemblies, said synchronizing means being adapted during the movements of the grate steps to maintain a predetermined clearance between the edge portions of the grate steps, said synchronizing means comprises an arm rigidly mounted at each of two adjacent shaft units which are adapted to pivot in opposite directions, said arms each being of a length slightly exceeding half the shaft spacing, being directed towards one another and being parallel in the parallel position of the grate steps supported by the shafts, and a link disposed between the free ends of the arms and preferably adjustable in length, said link being adapted in said parallel position to extend at right angles to the line of junction between the shafts.
 2. A grate according to claim 1, wherein the grate steps are adapted to pivot through an angle of 60*, each arm is adapted to rock through an angle of 30* in each direction from the position in which the two arms are parallel, and in their parallel position said arms make an angle of 15* with the line of junction between the shafts of the grate steps.
 3. A grate according to claim 1, wherein the adjustable link serves to control the clearance between the mutually overlapping edge portions of the grate steps in the neutral position thereof.
 4. A grate according to claim 1, wherein the shafts of the grate steps have associated with them lever arms which are interconnected by rigid links so that the shafts of the grate steps which pivot in the same direction constitute a group united by means of links.
 5. A grate according to claim 4, wherein the lever arms are adapted to actuate the shafts of the grate steps via spring means.
 6. A grate according to claim 1, wherein the movements causing the shafts of the grate steps to rock are provided with the aid of a hydraulic cylinder and piston assembly or like speed-controllable drive unit.
 7. A grate according to claim 1, wherein the rods collectively forming the grate steps at their ends have portions which project obliquely in opposite directions.
 8. A movable grate for furnaces, incinerators and the like in which a plurality of grate portions or grate steps are relatively movable in opposite directions and together constitute an inclined grate surface comprising one or more sections, drive means connected with said grate steps and operable to move the latter in opposite directions whereby a wavelike movement is imparted to the refuse to be incinerated on the grate so that said refuse is fed downwardly, said grate steps being disposed generally transversely of the inclination of the grate surface and suitably brought together in groups or sections, each of said grate steps inturn comprising a grate shaft supported by a shaft assembly, each of said grate shafts being generally centrally disposed of its respective grate step, each of said grate shafts being nonradially displaceable, and each grate step is arranged to pivot about said radially nondisplaceable and centrally disposed shaft, said shaft assemblies supporting the grate steps within a portion of the grate where the steps are adapted to move at the same rate, said drive means producing rocking of the grate steps, said drive means including transmission means actuating said shaft assemblies to rock the latter in opposite directions, and means synchronizing the pivoting movement of the shaft assemblies, disposed between two juxtaposed shaft assemblies, said synchronizing means being adapted during the movements of the grate steps to maintain a predetermined clearance between the edge portions of the grate steps.
 9. A grate according to claim 8, wherein the shaft of each grate step, to permit a central localization of the shaft relative to the step which has symmetrical cross section and is composed of a plurality of rods, comprises a journal arranged at each end and an intermediary portion which is radially offset in the manner of a crank and to which said rods are secured. 